This is the dream: Motorists on New York Avenue crest the railroad bridge and peer straight over the center field fence to the baseball diamond below, perhaps even catching a glimpse of the batter on a game day. Stores, restaurants and coffee shops bustle beyond the stadium with round-the-clock urban energy. Washington's eastern gateway, at long last, beckons visitors rather than frightens them.

It's a long way from today's reality. The view from that railroad bridge is now of a methadone clinic and a jumble of mismatched, charmless buildings. Junkies -- some recovering, some not -- jam the street corners, loitering in front of the liquor stores. Empty lots are strewn with rubble. Broken glass and garbage cover the sidewalks, reminding all who pass that some neighborhoods ravaged by white flight in the 1960s have never come back.

Those charting the future of the city, led by Mayor Anthony A. Williams (D), see not squalor but the potential offered by the development already beginning to transform a run-down area. All it needs, they say, is a push in the form of a $430 million baseball stadium.

"Put a baseball stadium there, it's real change," said D.C. Planning Director Andrew Altman. "This isn't just a planner's dream."

Williams is leading a delegation Thursday to meet with Major League Baseball officials in Phoenix to bid to move the ailing Montreal Expos to Washington for the 2004 season. City officials plan to present two other sites as well, but Williams prefers the one on New York Avenue, as do baseball officials because of its proximity to downtown.

Also bidding will be officials from Portland, Ore., and Northern Virginia, where ballpark planners are considering sites on the banks of the Potomac River in Rosslyn, near Dulles International Airport and in the Pentagon City area.

Yesterday, Arlingtonians for Baseball in D.C., a group of people who live near the proposed sites, told the Arlington County Board that a stadium in the county did not make economic sense and would be a poor use of public land. Board Chairman Paul Ferguson (D) said county officials have not been presented with a stadium plan and could not comment. Meanwhile, pro stadium activists asked the board to keep an open mind on any potential proposals."

Baseball officials have pointedly left open the possibility of keeping the team in Montreal if none of the bidders offers the kind of stadium deal they are seeking.

The key to the mayor's bid is obtaining support on the D.C. Council for a stadium financing package worth as much as $300 million at a time when officials project a budget shortfall nearly that large through the end of next year. Some D.C. Council members have said they see little or no money available to dedicate to a stadium whose transformative powers, they say, are vastly overstated by Williams.

"Nada. Cannot do it," said council member Sharon Ambrose (D), whose Ward 6 includes most of the area around the stadium site. "We have so little in the way of resources. And I'm not at all convinced that it brings in the kind of revenue they say it does."

She is not alone. Economists who have studied stadiums say they rarely generate enough new economic activity to support themselves and, like a public park, actually consume tax dollars that could be used for other purposes. Williams counters that the stadium would not use any existing revenue but would tap new sources it generates, such as taxes on tickets and the salaries of players, with the rest being paid by a new fee on larger businesses that would be politically unpalatable for anything but an economic development project.

Some don't buy it. "If businesses are willing to cough up extra money for baseball, then why not for more pressing needs?" said Ed Lazere of the D.C. Fiscal Policy Institute, a think tank that lobbies for better city services.

He and others contend that the New York Avenue corridor will redevelop anyway over the next few years with the opening of the federal Bureau of Alcohol, Tobacco and Firearms headquarters and other projects built recently or on the drawing board. Among them is a Metro stop, under construction now, that will be a block from the proposed stadium site.

Even if Williams can win over the doubters on the council and persuade Major League Baseball to move the Expos to Washington, serious obstacles exist to a stadium on New York Avenue -- not least of which is the choking traffic that runs along the northern edge of the site.

Forty-two thousand cars cross the intersection of New York and Florida avenues each day, for an average of 1,750 an hour and far more at peak hours. City officials are counting on two of every three baseball fans using the Metro, buses or the commuter lines that come to Union Station, a short walk south. But they estimate that 6,000 extra cars would fill roadways before and after games, enough to make a congested intersection worse.

Robert L. Johnson, the founder of Black Entertainment Television and one of the possible bidders for a team, travels New York Avenue routinely because the company is not far from the stadium site. "That traffic can get really backed up," he said. "But traffic flow usually leads to development because you've got more people moving through the corridor, and that means more opportunity for business. I think overall it's a big plus."

D.C. transportation officials are studying the intersection with an eye to possibly building a Dupont-type traffic circle, with New York Avenue passing underneath and Florida circling around. Transportation Director Dan Tangherlini estimated the cost at $50 million but argued that a stadium would neither add to that cost nor make some kind of solution there more urgent.

Aside from traffic, stadium builders would face the tricky logistics of acquiring at least 10 acres from several private owners, though the city owns some parcels as well. There is also the possibility of serious opposition from a community accustomed to low housing costs and subsidized rents. Some residents and merchants see a stadium as the latest tool of gentrification to push working-class blacks east into Maryland and make this section of the city an enclave for rich whites.

"If they put up a stadium, you know the community is gone," said Jim Brown, president of the residents association at Tyler House, an apartment building with subsidized rents across North Capitol Street from the proposed stadium site. "These people have been living here for a long time."

But city planners, while contending that existing residents can be protected, say some change is already on the way. Downtown is pushing east along New York Avenue and north, from Union Station, up North Capitol Street.

The stadium, they say, might be the best chance to make the area a vibrant, mixed-use community of shops and housing, instead of a stale office district that closes at night and on weekends. Developers already have bet on change, snatching up parcels throughout the area. XM Satellite Radio recently put its headquarters nearby, and a former Peoples Drugstore warehouse has been revamped into an office building occupied largely by city agencies.

Yet they remain islands among the blight. If workers wanted to lunch out, for example, they would find that the only sit-down restaurants in the neighborhood are a Wendy's and a McDonald's known as the McPharmacy because of the drug dealing in its parking lot.

One recent afternoon, Edwin B. Brown, an official with North Capitol Neighborhood Development Inc., a nonprofit group seeking to revive the area, walked the blocks where North Capitol Street crisscrosses with Florida and New York avenues. He stepped past the empty bottles of Mad Dog 20/20, gingerly crossed the tangle of intersections and smiled.

"All around that triangle," Brown said, "we see opportunities."

Staff writer Chris L. Jenkins contributed to this report.